Feeding mechanism for rock drills



y Jan. 4, l938. J. c. CURTIS FEEDING MECHANISM FOR ROCK DRILLS Filed Aug. 1 2, 1955 2 Sheets-Sheet l W fm INVENTOR lATTORNEY Jan..4, 1938. .1. c. CURTIS FEEDING MECHANISM FOR ROCK DRILLS Filed Aug. l2, 1955 2 Sheets-Sheevt 2 JOHN C. CURTIS INVENTOR ATTORNEY Patented Jan. 4, 1938 UNiriio stares `2,104,712 genome MsoHANisM Fon' BooK DRILLs .Fehn C. Curtis, Garfield Heights, Ohio, assigner to The Cieveland Rock Drill Company, Cleveland, Ghia, a corporation of Ollio .ieeaesaoniiugust 12, 1935, sei-iai No. 35,717

30 Claims.

- away from the work.

Another object of this invention is to produce a feeding mechanism for a rock drill wherein the latter is capable of relatively long feed toward or away from the work, without increasing the Y overall length of the assembly.

Another object of this invention is to utilise the force of the jars imparted to the rock drill due to the reversal oi the piston strokes therein, for feeding the drill in either direction.

@ther objects and advantages more or less ancillary to the foregoing and the manner in which the various objects are attained, reside in the specic construction and aggroupment of the elements peculiar to this structure, as will become apparent from a more complete examination of this specification, in the claims of which there are assembled certain specific combinations of parts and specific constructions indicative of the scope and spirit of the invention.

In the drawings which illustrate a preferred form of the invention:

Fig. l is a side elevational view of a rock drill having the invention applied thereto, the support being shown in section to illustrate details of construction.

Fig. 2 is an enlarged cross sectional view taken through a plane indicated by line 2 2 in Fig. l, the operative parts of the mechanism being shown in position for feeding motion of the rock drill away from the work.

Fig. 3 is a cross sectional view taken through a plane indicated by line 3-3 in Fig. 2, the operative parts of the mechanism being shown in position for feeding motion of the rock drill toward the work.

Fig. 8 is also a cross sectional view taken (ci. 121-9) Y througha plane indicated by line88 in Fig. 2. Fig. 9 is an enlarged top plan view of the left end portion of the mechanism shown in Fig. 1.

Referring to the drawings, I5 indicates a fluid actuated rock drill or drilling motor of the percussive type, which is slidably mounted within guideways I6 formed in the upper end of the side walls of a shell I1. Rotatably mounted within the usual back head I8 of the drilling motor I5, there is a throttle valve I9 formed with aV central bore 20. This bore is capable of communication withl an inlet chamber through a throttle port 2l or 22, and back head port 23. The back head I8 has'also incorporated therein a valve mechanism comprising a valve casing 24 formed with a cylindrical bore 25 extending therethrough, and enlarged at one end to form a counterbore 26. Provided within the back head I8 around the valve casing 24, there is an annular groove 21, which .opens into the bottom of the counterbore 26 through a port 28. Between its ends, the bore 25 is provided with an internal annular groove 29 in constant communication with a port,3ll- Leading from the extreme end of the bore 25, there is a port 3| leading to the atmosphere through a port 32. Slidably mounted within the bore 25 in fluid tight engagement with the inner wall thereof, there is a valve 33 terminated at one end by a restricted stem 34. The other end of they valve is provided with a flange 35 slidably mounted within the counterbore 23, anda small annular step 36, the purpose of which will be explained later. Through the flange 35, there is a plurality of small ports 31. The counterbore 26 of the valve casing 24 is normally closed by the front, face of a housing 38 secured in abutment with the back head I8 by the usual side bolts 3S. This housing has a port 40 leading from the central portion of the counterbore 2t'. This last port is in communication with the port 30, through a passage 4I i The housing is provided with an enlarged counterbore 42 disposed vertically with respect to the drilling motor I5. Mounted within the counterbore 42, there are two identical rings 43 and 44, the latter located on top of the former. The inner wall of each ring is formed with ratchet teeth 45, while the external wall thereof is shaped to constitute worm gear teeth 45. Rotatably mounted within the two rings 43 and 44, there is an element 41 of a height substantially equal to the combined height of the two rings. This element carries two sets of four pawls 48 and 49. The pawls 48 are located for engagementwith the ratchet teeth of the ring 43,

and are constantly urged into engagement therewith by spring pressed plungers 59 also carried by the element 41. The pawls 49 located on top of the pawls 48 are capable of engagement with the ratchet teeth 45 of the ring 44, and are also constantly urged into engagement therewith by spring pressed plungers The element 41 is provided with a centrally disposed vertical splined bore 52, adapted to slidably receive a correspondingly splined shaft 53. From the element 41, the shaft 53 extends through the lower portion of the housing 38, where it is laterally guided within a bushing 54. The lower endof the shaft 53 depending from the housing 38 is enlarged and machined to form a pinion 55. The upper end portion of the shaft 53 is threaded to receive a relatively wide washer 56, which is slidably mounted within a cap 51 secured to the housing 38 by bolts 58. The washer 56 is provided 'with a circumferentially disposed groove 59 having a segment 68 loosely mounted therein. Rotatably mountedwithin the cap 51 on an axis parallel to the longitudinal center axis of the drilling motor |5, there is a cylindrical member 6| having a handle 62 secured to one end thereof. The member 6l has the other end portion thereof machined eccentrically to form a finger 63, which is rotatably mounted within a radial bore formed through the segment 60. The circumferential wall of the member 6| is provided with a plurality of carefully spaced V-shaped grooves 64, adapted to receive the correspondingly shaped end of a spring pressed plunger 65. The washer 56 is engageable with'a brake lining Washer 66, secured to the bottom of the cap 51 by rivets 61.

In operative engagement with the worm gear teeth 46 of the ring 44, there are the teeth of a cylindrical rack 68 which is reciprocably mounted within a bore 69 formed within the housing 38. This rack is provided at one end with an enlarged cylindrical head 1B, which is reciprocably mounted within a chamber 1| located in coaxial alignment with the bore 69. The cylindrical rack 68 and head 16 are integrally secured to each other to form a power actuated member or piston imparting rotation to the ring 44 in the manner hereinafter described. The chamber 1| is closed by a plug 12, which has a small step 13 extending therefrom into the chamber 1| assuring thereby a space between the plug and the head of the rack 68. The port 40 opening into the valve casing counterbore 26, leads therefrom into' the chamber 1| adjacent the plug 12. Intermediate the ends of the chamber 1|, there is a small vent 14 which leads to the atmosphere. The cylindrical rack 68 isV constantly urged toward the plug 12 by a compression spring 15, which has one end seated on the bottom of the bore 69, while the other end thereof is engaging the bottom of a bore 16 formed within rack 68.

Engaging the worm gear teeth 46 of the ring 43, there are the teeth of a relatively short cylindrical rack 11 located within a flat bottom bore 18 provided within the housing 38. The travel of this rack in one direction is prevented due to the engagement of the end thereof with the flat bottom of the bore 18, while the travel in the other direction is checked by a heavy compression spring 19 located between the rack and the plug 80 closing the bore 18.

The shell has welded to the extreme end of the external side walls thereof, lugs 8| adapted to receive the free ends of a U-shaped bolt 82 which is secured thereto by nuts 83. This bolt constitutes a handle, and has the side arms thereof provided with integral collars 84 engaging a cross plate 85, for securing the same to the rear end of the shell. Similarly secured to the front end of the shell, there is a handle 86 and cross plate 81. Secured to the upper end of one of the inner side walls of the shell, there is a rack 88, and to the lower end of the other inner side wall of the shell, there is a similar rack 89 forming with the rack 88 feed engaging means extending substantially the full length of the shell. The end portions of the racks, which are turned cylindrical and threaded, are protruding through the cross plates 85 and 81, to which they are secured by nuts 90. The pinion 55 is capable of operative engagement with either the rack 88 or 89, as will be explained hereinafter.

Referring again to the throttle valve |9, it will be seen that the latter is provided with a semiannular groove 9| in constant communication with the center bore thereof through a radial port 92. From the throttle valve 9, there is a port 93 leading into the annular groove 21 formed around the Valve casing 24.

In the operation of the device, assuming that the throttle valve |9 is positioned as shown in Fig. 8, and that the valve 33 is positioned as shown in Fig. 3, pressure fluid from the center bore of the throttle valve will flow through the port 92 into the groove 9|, from where it will be admitted into the annular groove 21 through the port 93. From the groove 21, the pressure fluid will flow into the valve casing counterbore 26 below the valve flange 35 through the port 28, and thereafter through the ports 31 on the other side of the valve flange 35, thus creating pressure on the large end of the valve for maintaining the same in the position shown in Fig. 3. Simultaneously the pressure fluid from the valve casing counterbore 26, will be admitted into the chamber 1| between the plug 12 and head 10, through the port 40. The pressure thus exerted on the head 18 of the cylindrical rack 68, will drive the latter against the effort of the compression spring 15, imparting thereby rotation to the ring 44 in a counterclockwise direction in Fig. 5. The pawls 49 engaging the ratchet tooth 45 of the ring 44, will transmit the rotation of the latter to the element which in turn will transmit rotation to the shaft 53 due to the spline engagement of the former with the latter, thus causing the rotation of the pinion 55 in the same direction as the element 41. The rotation of the element 41 in a counterclockwise direction in Figs. 5 and 6, will cause the pawls 48 to ride over the ratchet teeth 45 of the ring 43, thus permitting the ring 43 to remain stationary. During the slidable movement of the cylindrical rack 68 toward the bottom. of the bore 69, the -head 10 will uncover the small vent 14, thus creating a drop of pressure between the plug 12 and head 19, and consequently causing also a drop of pressure in the valve casing counterbore 26 through the port 40. 'I'he pressure fluid acting on the restricted area of the valve flange 36, will now kick the valve in the position shown in Fig. 4, closing the port 40. In this position of the valve, the pressure uid remaining in the chamber 1| and port 4D, is now free to exhaust to the atmosphere Via the ports 4| and 30, groove 29 and ports 3| and 32, permitting thereby a free return of the cylindrical rack 68 in the position shown in Fig. 5. During this return movement of the cylindrical rack 68, rotation in a clockwise direction in Fig. 5 is imparted to the ring 44. During this rotation of the ring 44, the pawls 49 will ride over the ratchet teeth 45 of element 41.

the ring 44, thus permitting the element 41 together with the shaft 53 .and pinion 55 to remain stationary. When the valveV 33 is positioned as shown in Fig. 4, the pressure fluid is still admitted on the rear face Vof the ange 36 through the small ports 31. The area of this rear face being larger than the area of the front face of the flange, the pressure fluid acting on the former will again kick the Valve into the position shown in Fig. 3, thus closing the communication of the exhaust port 3| with the groove 30, and opening the port 40 for again admitting pressure fluid into the chamber 1I to actuate the cylindrical rack 68 toward the bottom of the bore 69, in the manner previously described.

. From the foregoing, it will be understood that an intermittent rotation in only one direction is imparted to the element 41, and consequently to the gear or pinion 55. When it is desired to feed the drilling motor toward the work, the rotating member 6I through its handle 62, is positioned as shown in Fig. 3, thus causing the engagement of the pinion 55 with the rack 88. The rotation imparted to the pinion 55 in a counterclockwise direction in the drawings, will obviously cause the slidable movement of the drilling motor toward the work. The rotating member 6I isA maintained in the position shown in Fig. 3 due to the location of .the spring pressed plunger 65 within one of the U-shaped grooves S4. When it is desired to reduce the feeding speed of the drilling motor toward the work, the member 6I may be rotated to bring its eccentric finger toward the extreme end of its upward travel relative to the longitudinal center axis of the member 6I, thus causing'the forcible engagement of the washer 56 with the brake lining 66, for slowing the speed of rotation of the pinion 55, and the speed of feeding motion of the drilling motor I5.

To feed the drilling motor away from the work, the member 6I and its eccentric finger 53 may be rotated about 180, causing thereby the slidable movement of the washer 56 into the position shown in Fig. 2. In this position of the washer 55, the pinion v55 is now engaging the rack B9, and due to the rotation of the former in a counterclockwise direction, the drilling motor I5 is fed away from the work.

When it is desired to lock the drilling motorY against longitudinal movement relative to the support or shell I1, the member 6I may be r0- tated about from the position shown in Fig. 3, thus positioning the washer 56 about halfway between the extreme ends of its travel within the cap 56, and causing the engagement of the pinion 55 with the racks 38 and 85. The pinion engaging the two racks is held against rotation, thus preventing the longitudinal movement of the drilling motor I5.

The above description is directed to the operation of the feeding mechanism irrespective of the operation of the drilling motor I5. However, when the drilling motor is in operation, that is, when the throttle valve I9 is positioned to alford the communication of the throttle port 22 with the port 23, the reversal of the piston strokes within the motor will impart jars to the motor Y tending to move the latter relatively to the shell in both directions, and consequently tending to impart oscillatory motion tothe pinion 55Y and During'the operation of the feeding device, since the pinion 55 is always rotated in a counterclockwise direction, it will be understood that the rotation imparted to the pinion inY that last mentioned direction due to the jars of the drilling motor, will assist the cylindrical rack 68 to feed the drill toward or away .from the work. However the rotation of the pinion in a clockwise direction imparted thereto due to the jars of the drilling motor, would tend tomove the motor into a direction adversed to the feeding motion imparted thereto by the cylindrical rack 58. Referring to Fig. 6, it will be seen that when the element 41 tends to rotate in a clockwise direction, the pawls 48 engaging the ratchet teeth 45 of the ring 4.3 will also tend to transmit rotation to the latter, thus causing the slidable movement of the cylindrical rack 11 toward the plug 80. However, the heavy compression spring 19 will prevent the slidable movement of the cylindrical rack 11, thus preventing the longitudinal motion of the drilling motor in a direction adversed to its feeding motion. The compression spring 19 while preventing the slidable movement of the cylindrical rack 11 will compress suiciently to absorb the shocks resulting from the jars imparted to the drilling motor, reducing thereby the wear and preventing possible breakage of the operative parts.

When the throttle Valve I9 is positioned to afford the communication of its port 2l with the port 23, the port 93 is closed by the throttle valve, preventing thereby the operation of the feeding mechanism during the operation of the drilling motor I5. In this instance the drilling motor is fed toward or away from the work, due to the jars imparted to the motor.. These jars, as previously explained, will tend to impart oscillatory motion to the pinion 55. Since the latter can only rotate in a counterclockwise direction, the motor will be free to move in one direction relative to the rack with which the pinion is engaged, the direction of movement of the motor being changed by shifting the pinion from one rack to the other.

From the foregoing, it will be understood that the drilling motor may be fed toward or away from the work by the feeding mechanism independently of the operation of the drilling motor, or due to the jars imparted to the latter independently of the operation of the feeding mechanism. It will be further understood that the rate of feeding speed of the motor in at least one direction may be controlled at will, and that the motor may be locked against movement relative to the support.

Although the foregoing description is necessarily of a detailed character, in order to completely set forth the invention, it is to be understood that the specific terminology is not intended to be restrictive or coniining, and it is to be further understood that various rearrangements of parts and modification of structural detail may be resorted to without departing from the scope or spirit of the inventionA as herein claimed. Y

I claim: Y

1. In a feeding device for a rock drill, the co1--- bination with a support and a drilling motor slidable with said motor for imparting forward and backward feeding motion thereto, said mechanism comprising a duality of tooth elements longi-V thereon, a feeding' mechanism associated.

with thel teeth of one or the other of said elements for causing forward or backward feeding motion of said motor due to the movement of said member relative to said motor.

2. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, a feeding mechanism associated with said motor for imparting forward and backward feeding motion thereto, said mechanism comprising a duality of racks longitudinally of the support, a gear carried by said motor capable of operative engagement with one or the other of said racks, power actuating means associated with said gear for imparting rotation thereto in a single direction, and operable means for selectively moving said gear in operative engagement with one or the other of said racks for causing the forward or backward feeding motion of said motor due to the rotation of said gear in one direction.

3. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, an elongated element longitudinally of said support, a member carried by said drilling motor, said element and member having means formed thereon capable of interengagement whereby the rotary motion of said member relative to said element causes the slidable movement of said drilling motor, a mechanism including a gear having a power actuated reciprocable rack associated therewith for imparting rotary motion thereto in alternative direction, and means for transmitting the rotary motion of said gear in one direction to said member irrespective of the rotary motion of the former in the other direction, causing thereby a. slide-ble movement of said drilling motor in one direction.

4. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, an elongated element longitudinally of said support, a rotatable member carried by said drilling motor, said element and member having means formed thereon capable of interengagement whereby the rotary motion of said member relative to said element causes the slidable movement of said drilling motor, a mechanism associated with said member including a power actuated reciprocable driving element operatively connected with a rotatable driven element for imparting oscillatory motion thereto, and means for transmitting the rotary motion of said driven element in one direction to said rotary member irrespective of the rotary motion of said driven element in the other direction, causing thereby a step by step slidable movement of said drilling motor.

5. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, a reciprocatory hammer piston in the motor imparting jars thereto to move the motor in two directions relative to the support, a power actuated mechanism associated with the motor for imparting feeding motion thereto, and cushioned means independent of said mechanism for preventing the movement of said motor in av direction adverse to that of its feeding motion;

6. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, a reciprocatory hammer piston in the motor imparting jars thereto to move the motor in two directions relative to the support, a rack longitudinally of the support, a gear carried by the motor in operative engagement with said rack, a power actuated mechanism asso-V ciated with said gear for impartingrotary motion thereto in Yone direction for feeding the motor longitudinally of Vthe support, and cushioned means independent of said mechanism associated with said gear for preventing the rotary motion thereof in the other direction, preventing thereby the longitudinal movement of the motor in a direction adverse to that of its feeding motion.

7. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, of a duality of racks longitudinally of said support, a gear carried by said motor capable of operative engagement with one or the other of said racks, a power actuated mechanism associated with said gear imparting rotation thereto in a single direction, said racks and gear arranged and disposed whereby the rotary engagement of said gear with one of said racks causes the feeding motion of said drilling motor in one direction and its rotary engagement with the other of said racks ca'uses the feeding motion of the drilling motor in the other direction, and means for shifting said gear in operative engagement with one or the other of said racks.

8. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, a reciprocatory hammer piston in the motor imparting jars thereto to move the motor in two directions relative to the support, a duality of racks longitudinally of said support, a gear carried by said motor capable of operative engagement with one or the other of said racks, the jar resulting movement of said motor tending to cause the rotation of said gear in both directions due to its operative engagement with one or the other of said racks, cushioned means for preventing the rotary motion of said gear in one direction permittingr thereby the movement of said motor in a` single direction during the operative engagement of said gear with one of said racks, and means for shifting said gear from one to the other of said racks, permitting thereby the movement of said motor in the other direction.

9. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, a reciprocatory hammer piston in the motor imparting jars thereto to move the motor in two directions relative to the support, a movement resisting mechanism associated with said motor for preventing the movement thereof in one direction, said mechanism including a duality of racks longitudinally of the support one higher than the other, and a gear rotatable in a single direction movable axially in operative engagement with one or the other of said racks for controlling the direction of movement of said motor. Y

l0. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, a reciprocatory hammer piston in the motor imparting jars thereto to move the motor in two directions relative to the support, a movement resisting mechanism associated with said motor, said mechanism including a duality of elements longitudinally of the support, a member carried by the motor for rotation on a stationary axis disposed in equidistant relation with said elements, means on said elements capable of interengagement with similar means on said member for .causing the rotation of the latter due to the movement of said motor, stop means associated with said member for preventing the rot-ation thereof in one direction, and operable means for causing the operative engagement of said member with one or the other of said elements to control the direction of movementof said motor.

11. In a feeding device for a rockdrill, the combination with a support and a drilling motor slidable thereon, a recip-rocatory hammer piston in the motor imparti-ng jars thereto to move the motor in two directions relative Vto the support, a mechanism associated with said motor for controlling tlie direction of movement thereof, said mechanism including a duality of toothed elements longitudinally of the support, and a member carried by said motor for movement therewith, s-aid member being slidable on an axis perpendicular to said moto-r for selective engagement with the teeth of one of said elements for preventing the movement of said motor in one direction and with the teeth of the other of said elements for preventing the movement of said motor in theother direction.

12. Infa feeding device for a rock drill, the

combination with a support formed with side n walls having guideways in the upper end thereof, a drilling motor slidable in said guideways, a reciprocatory hammer piston in the'motor imparting jars thereto to move the motor in two directions relative to the support, a mechanism associated with said motor for controlling the direction of movement thereof, said mechanism including a rack secured to the upper end of one of the side walls of said support, another rack secured to the lower end of the other of said side walls, a rotatable gear carried by said motor Vfor movement therewith between the side walls of said support, said gear being axially movable in operative engagement with one or the other of said racks, stop means associated with said gear for preventing the rotation of said gear in one direction irrespective of the direction of movement of said motor, and operable means for selectively causing the engagement of said gear with one or the other of said racks, controlling thereby the direction of movement of said motor.

13. In a drilling apparatus, the combination with a support and a drilling motor slidable thereon, areciprocatory hammer piston in the motor imparting jars thereto to move the motor in two directionsv relative to the support, and a movement resisting mechanism associated with said motor, said mechanism including a duality of stationary racks disposed in opposition to each other, and a gear carried by said motor movable in engagement with both of said racks for preventing the movement of said motor.

14, Ina feeding device for a rock drill, rthe combination with a support and a drilling motor slidable thereon, a reciprocatory hammer piston in the motor imparting jars thereto to move the motor in two directions relative to the support, a duality of racks longitudinally of the support, a gear rotatably carried by said motor capable of engagement with one or the other of said racks, stop means associated with said gear for preventing the rotation thereof in one direction, and means associated with said gear operable for causing the travel thereof from one to the other of said racks for controlling the direction of movement of said motor, said last means being operable for positioning said gear substantially halfway between the ends of the travel aforesaid, causing thereby the engagement of the gear with both of said racks for locking the motor against movement relative to the support.

15. In a feeding device for a rock drill, the

combination with a 'support' and a drilling motor slidable thereon, a reciprocatory hammer piston in the motor imparting jars thereto to move the motor in two directions relative to the support, a duality of racks longitudinally of the support, a gear rotatably carried by said motor engageable with one or the other of said racks, stop means associated with said gear for preventing the rotation thereof in one direction, said racks and gear arranged and disposed whereby the movement of said motor in one direction is prevented due to the engagement of said gear with Y one of said racks and'in the other direction due to theengagement of said gear with the other of said racks, and means associated with said gear for controllingthe rate of rspeed of said motor in one direction.

16. In a feeding device fora rock drill, the combination with a support and a drilling motor slidable thereon, of a Yfeeding mechanism for said motor comprising a duality of racks longitudinally of said support, a power/actuated gear rotatable in a single direction, said racks and gear arranged and disposed whereby the rotary engagement ofsaid gear with one or the other of said racks causes `the. forward or rearward feeding motion of said motor, means for selectively causing the rotary'engagementv of said gear with one or the other of said racks, and friction means associated with said gear for controlling the rate of feeding speed of said motor in one direction.

17. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, a stationary rack, a. power actuated gear'carried by the motor and meshing with the rack forV actuating said motor in one directiomand cushioned means independent of the power actuating said `gear for preventing the rotation thereof in the other direction.

18. In a feeding device for a rock drill,V the combination with a support and a drilling motor slidable thereon, of a duality of stationary elements, of a power actuated member carried by said motor for lmovement in a single direction, said member being operatively engageable with one or the other of said elements for feeding said motor in one or the other direction, and means operable for selectively lcontrolling the engagement of said member with one or the other. of said elements, controliing thereby the direction of feeding motion of said motor.

19.'In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, of a power actuated gear carried by said motor for rotation in a single direction, toothed means on said support with which said gear is engageable for feeding said motor in `one or the other direction, and means operable for selectively controllingthe direction of feeding motion'ofsaid motor irrespective of the rotation of said gear in a single direction.

20. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, feed engaging means carried by said support, a power actuated element carried by the motor for movement in a single direction engageable with said feed engaging means for transmitting feeding motion to said motor in one or the other direction and means for selectively controlling the engagement of said element with said feed engaging means.

21. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, a power actuated feeding mechanism associated with said support and motor for imparting feeding motion to the latter in one direction, and locking means independent ofthe power actuating said mechanism for preventing the movement of the motor in the other direction.

22. In a feeding device for a rock drill, the combination with a support and a drilling motor slidable thereon, of a duality of interengaging ele-A ments operatively associated with the support and the motor, a fluid actuated mechanism associated with one of said elements for automatically imparting an intermittent movement thereto relative to the other for effecting a step by step feeding movement in one direction of the motor due to the interengagement of said elements, and locking means independent of the power actuating said mechanism for preventing the movement of the motor in the other direction.

23. In a feeding mechanism for a rock drill, the combination of a support and a drilling motor slidable thereon, a duality of elements operatively associated with the support and the motor, interengagable means on said elements whereby the rotation of one relative to the other causes the slidable movement of the motor on the support, a ring having one set of internal and one set of external teeth formed thereon, a power actuated reciprocable member operatively assocated with one set of said teeth for imparting rotation to said ring, and means operatively associated with the other set of said teeth for transmitting the rotation of said ring to one of said elements for electing the slidable movement of the motor relative to the support.

24. In a rock drill, the combination with a support and a motor slidable thereon, of feeding means for said motor including interengageable elements operatively associated with the support and the motor whereby the rotation of one element relative to the other causes the slidable movement of the motor, a mechanism including a rotatable member and a power actuated reciprocable piston operatively associated with said member for imparting rotation thereto, traction means on said member, and means operatively associated with said traction means and one of said elements for transmitting rotation thereto causing the slidable movement of the motor.

25. In a rock drill, the combination with a support and a motor slidable thereon, of feeding means for said motor including a rotatable and a stationary interengaging element operatively associated with the support and the motor whereby the rotation of the rotatable element relative to the other causes the slidable movement of the motor, a mechanism including a power actuated reciprocable piston operatively associated with said rotatable element for imparting rotation thereto during one stroke of the piston, and means for locking said element against adverse rotation during the return stroke of said piston@ 26. In a feeding mechanism for a rook drill, the combination with a support and a drilling motor slidable thereon, stationary means carried by the support havinga rotatable element active thereupon and carried by the motor for moving the motor relative to the support, a uid actuated reciprocable member, and means responsive to the reciprocatory movement of said member for effecting the rotation of said element in one direction, said means including a ratchet mechanism having a toothed ring acted upon by said member and pawls engageable with the teeth of said ring for controlling the drectionof rotation of said` element.

27. In a rock drill, the rcombination with a support and a motor slidable thereon, of a feeding mechanism forsaid motor including a rotatable element carried by the motor, means longitudinal of the supportcooperating with said element for effecting the feeding motion of the motor due to the rotation of said element, a power actuated reciprocatory member operatively associated with said element for imparting rotation thereto, fand' means for selectively controlling the direction of the feeding motion of said motor.

f 28. The combination with a support having a drill slidable thereon, of feeding means for the drill comprising a rotatable element carried by the motor, stationary means port having said element active thereon for feeding the drill relative to the support, means for intermittently rotating said element for effecting a'step by step feeding motion of said drill including a motor having relatively movable members one of which is actuated by fluid pressure for reciprocation longitudinally of the support, and means for selectively controlling the direction of feeding motion of the drill.

29. The combination with a drilling motor having a hammer reciprocable therein, of feeding means for said motor comprising a housing, a fluid actuated piston reciprocable Within said housing, means deriving motion from the reciprocation of said piston for transmitting a step by step feeding motion to said motor, and means for selectively controlling the direction of said feeding motion.

30. rThe combination with a drilling motor having a hammer reciprocableV therein, of feeding means for said drill comprising a housing, a fluid actuated piston reciprocable within said housing, means including an element deriving rotation in one direction from the working stroke of said j piston, means for locking said element against rotation in the other direction during the return stroke of said piston, and means responsive to the rotation of said element for eiecting a step by step feeding motion of said motor.

JOHN C. CURTIS.

carried by the sup- 

